Telephone



'12Ai EDISON. TELEPHONE.

\ No. 252,442. H Patented half/1,1381

PATENT OFFICE.

THOMAS A.EDISON, OF MENLO PARK, NEW JERSEY.

TELEPHONE.

SPECIFICATION forming para of Letters Paten No. 252,442,` dated January 1'?, 1882.

l Application filed August G, 1879. i l i I To all whom it may concern Be it known that I, THOMAS ALVA"EDIsoN, of Menlo Park, in the State of New Jersey, have invented an Improvement in Telephones, ot' which the following is a specification.

In this telephone the button of nelydivided uconducting material is between metal cups on arms secured to the diaphragm, and the pressure ou the carbon button is varied bythe outward movement of the diaphragm, causing` t-he ends of the arms to move slightly outward and lessen the pressure ou the carbon, and this pressure is increased when the ends of the arms are brought toward each other bythe return movement of the diaphragm.

In the drawing I have shown a horizontal section of the telephone. The mouthpiece a and diaphragm b are of usual character. cc are metal arms or supports secured tothe diaphragm b, andthe ends of these arms4 are made as cups to receive the carbon button e. One of these arms is insulated from, said diaphragm, so that the current passes by Wirel, arm c, carbon e, arm c, and wire 2 to line. The ends of the arms or supports c c are kept pressed against the ends ofthe carbon button either Vby the spring ofthe arms or by a rubber baud,h, passed around the springarms.

When a sound-wave strikes the diaphragm the ends ot the. arms to be farther apart than when the' diaphragm is at rest; consequently the pressure on the carbon is lessened, and thus weakens the electric current passing over the line; but as the diaphragm returns to its normal position the ends ofthe arms are again drawn toward each other, and increase the.

pressure on the carbon button, and the tension of the electric current n the line is also increased. Thus all the sound-waves striking the diaphragm are translated into electric waves of corresponding character as topitch and amplitude. i

the diaphragm is bowed outwardly and causes i 

